Added a sample for Facebook App Login and Graph API (insights) call

Change-Id: Ie719bb118a98d4794d5da6c9aad2a281c7caf413

src/test/java/org/scribe/examples/FacebookAppLoginExample.java

@@ -0,0 +1,71 @@
+package org.scribe.examples;
+
+import java.util.Scanner;
+
+import org.scribe.builder.ServiceBuilder;
+import org.scribe.builder.api.FacebookApi;
+import org.scribe.model.OAuthRequest;
+import org.scribe.model.Response;
+import org.scribe.model.Token;
+import org.scribe.model.Verb;
+import org.scribe.model.Verifier;
+import org.scribe.oauth.OAuthService;
+
+public class FacebookAppLoginExample 
+{
+   private static final String NETWORK_NAME = "Facebook";
+  private static final Token EMPTY_TOKEN = null;
+  private static final String PROTECTED_RESOURCE_URL ="https://graph.facebook.com/%s/insights";
+
+
+  public static void main(String[] args)
+  {
+    // Replace these with your own api key and secret
+    String apiKey = "your_app_id";
+    String apiSecret = "your_api_secret";
+    String callbackURL = "your_call_back";
+    OAuthService service = new ServiceBuilder()
+                                  .provider(FacebookApi.class)
+                                  .apiKey(apiKey)
+                                  .apiSecret(apiSecret)
+                                  .callback(callbackURL)
+                                  .grantType(FacebookApi.GRANT_TYPE_CLIENT_CREDENTIALS)
+                                  .build();
+    Scanner in = new Scanner(System.in);
+
+    System.out.println("=== " + NETWORK_NAME + "'s OAuth Workflow ===");
+    System.out.println();
+
+    // Obtain the Authorization URL for App Login
+    System.out.println("Fetching the Authorization URL...");
+    String authorizationUrl = service.getAuthorizationUrl(EMPTY_TOKEN);
+    System.out.println("Got the Authorization URL!");
+    System.out.println("Now go and authorize Scribe here:");	
+    System.out.println(authorizationUrl);
+    System.out.println("And paste the authorization code (see url and find &code=...) here");
+    System.out.print(">>");
+    Verifier verifier = new Verifier(in.nextLine());
+    System.out.println();
+
+    // Trade the Request Token and Verfier for the Access Token
+    System.out.println("Trading the Request Token for an Access Token...");
+    Token accessToken = service.getAccessToken(EMPTY_TOKEN, verifier);
+    System.out.println("Got the Access Token!");
+    System.out.println("(if your curious it looks like this: " + accessToken + " )");
+    System.out.println();
+
+    // Now let's go and ask for a protected resource!
+    System.out.println("Now we're going to access a protected resource...");
+    OAuthRequest request = new OAuthRequest(Verb.GET, String.format(PROTECTED_RESOURCE_URL,apiKey));
+    service.signRequest(accessToken, request);
+    Response response = request.send();
+    System.out.println("Got it! Lets see what we found...");
+    System.out.println();
+    System.out.println(response.getCode());
+    System.out.println(response.getBody());
+
+    System.out.println();
+    System.out.println("Thats it man! Go and build something awesome with Scribe! :)");
+
+  }
+}